The proposed research will involve the comparative testing in normal and tumor-bearing animals of experimental vaccines and subcellular fractions from anaerobic coryneforms. We hope to establish in this way that tests of reticulo-stimulatory ability in normal animals can be reliable indicator of tumor-inhibitory activity. If this is so, it should help to clarify the mechanisms of tumor-inhibition. It is also proposed to examine vaccines from other groups of Gram positive bacteria.